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Shahid M, I . M, Khan S, Mehtab M, Yadav O, Ansari A, Qasem KM, Ahmed A, Saniya M, Akhtar MN, AlDamen MA. Elucidating the contribution of solvent on the catecholase activity in a mononuclear Cu(II) system: An experimental and theoretical approach. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130878] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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2
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I M, Zeeshan M, Yadav O, Ansari A, Qasem KMA, Akhtar MN, AlDamen MA, Shahid M. Structure, DFT studies and evaluation of catechol oxidase (CO) mimic activity of mononuclear Co(II) complexes derived from aminoalcohols: an experimental and theoretical approach. J Biomol Struct Dyn 2021; 40:8740-8751. [PMID: 33955333 DOI: 10.1080/07391102.2021.1916598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The impetus to modeling of enzyme mimics comes from their potential to provide insight to the alternate mechanistic pathways of the native enzymes. The present study demonstrates the syntheses and characterization of two different cobalt(II) complexes, [Co(pdm)(Phen)Cl]Cl·H2O (1) and [Co(pmmH)2(SCN)2] (2) with the aminoalcohol ligands such as pyridine-2,6-dimethanol (pdmH2) or 2-pyridinemonomethanol (pmmH) and their assessment as catechol oxidase (CO) enzyme mimic. Single Crystal X-ray diffraction and powder X-ray diffraction data suggest the octahedral environment around the Co(II) ion and the complexes form extensive 1D or 2D propagating network as a result of non-covalent interactions (O···H and C-H···π). TD-DFT calculations were used to explain the spectral bands obtained during the UV-Vis absorption studies and it is ascertained that the transitions were mainly of the intra-ligand charge transfer (ILCT) type. The catecholase biomimetic catalytic activity of the synthesized complexes has been investigated in detail and the kinetics is also performed. The results obtained show that both the complexes catalyze the aerobic oxidation of catechol to the corresponding o-quinone. The Kcat value for 1 is 106.99 h‒1 and for 2 is 90.32 h‒1 in methanol. It may be mentioned here that 1 and 2 are effective catalysts, with the order of activity being 1 > 2. The order of enzymatic activity is well justified by CV and DFT studies.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Mantasha I
- Functional Inorganic Materials Lab (FIML), Department of Chemistry, Aligarh Muslim University, Aligarh, India
| | - Mohd Zeeshan
- Functional Inorganic Materials Lab (FIML), Department of Chemistry, Aligarh Muslim University, Aligarh, India
| | - Oval Yadav
- Department of Chemistry, Central University of Haryana, Mahendergarh, Haryana, India
| | - Azaj Ansari
- Department of Chemistry, Central University of Haryana, Mahendergarh, Haryana, India
| | - Khalil M A Qasem
- Functional Inorganic Materials Lab (FIML), Department of Chemistry, Aligarh Muslim University, Aligarh, India
| | - Muhammad Nadeem Akhtar
- Division of Inorganic Chemistry, Institute of Chemistry, Baghdad-ul-Jadeed Campus, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - Murad A AlDamen
- Department of Chemistry, School of Science, the University of Jordan, Amman, Jordan
| | - M Shahid
- Functional Inorganic Materials Lab (FIML), Department of Chemistry, Aligarh Muslim University, Aligarh, India
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I. M, Shahid M, Kumar M, Ansari A, Akhtar MN, AlDamen MA, Song Y, Ahmad M, Khan IM. Exploring solvent dependent catecholase activity in transition metal complexes: an experimental and theoretical approach. NEW J CHEM 2020. [DOI: 10.1039/c9nj04374h] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Four coordination compounds are designed with pyridinemethanol ligands, characterized with spectral, magnetic and X-ray analyses, and assessed for catecholase activity in various solvents.
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Affiliation(s)
- Mantasha I.
- Department of Chemistry
- Aligarh Muslim University
- Aligarh-202002
- India
| | - M. Shahid
- Department of Chemistry
- Aligarh Muslim University
- Aligarh-202002
- India
| | - Manjeet Kumar
- Department of Chemistry
- Central University of Haryana
- Mahendergarh-123031
- India
| | - Azaj Ansari
- Department of Chemistry
- Central University of Haryana
- Mahendergarh-123031
- India
| | - Muhammad Nadeem Akhtar
- Department of Chemistry
- Khwaja Fareed University of Engineering & Information Technology
- Rahim Yar Khan 64200
- Pakistan
| | - Murad A. AlDamen
- Department of Chemistry
- Faculty of Science
- The University of Jordan
- Amman 11942
- Jordan
| | - You Song
- State Key Laboratory of Coordination Chemistry
- Nanjing University
- Nanjing 210023
- P. R. China
| | - Musheer Ahmad
- Department of Applied Chemistry (ZHCET)
- Aligarh Muslim University
- Aligarh-202002
- India
| | - Ishaat M. Khan
- Department of Chemistry
- Aligarh Muslim University
- Aligarh-202002
- India
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Gao WS, Wang JM, Shi NN, Chen CN, Fan YH, Wang M. Electrocatalytic water oxidation studies of a tetranuclear Cu(ii) complex with cubane-like core Cu4(μ3-O)4. NEW J CHEM 2019. [DOI: 10.1039/c8nj06263c] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A bio-inspired cubane-like tetranuclear cluster [Cu4(pdmH)4(OAc)2](NO3)2·3H2O can electrocatalyze water oxidation under aqueous alkaline conditions through a PCET process.
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Affiliation(s)
- Wei-Song Gao
- Key Laboratory of Marine Chemistry Theory and Technology
- Ministry of Education
- College of Chemistry and Chemical Engineering
- Ocean University of China
- Qingdao
| | - Jin-Miao Wang
- Key Laboratory of Marine Chemistry Theory and Technology
- Ministry of Education
- College of Chemistry and Chemical Engineering
- Ocean University of China
- Qingdao
| | - Ning-Ning Shi
- Key Laboratory of Marine Chemistry Theory and Technology
- Ministry of Education
- College of Chemistry and Chemical Engineering
- Ocean University of China
- Qingdao
| | - Chang-Neng Chen
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- The Chinese Academy of Sciences
- Fuzhou
- China
| | - Yu-Hua Fan
- Key Laboratory of Marine Chemistry Theory and Technology
- Ministry of Education
- College of Chemistry and Chemical Engineering
- Ocean University of China
- Qingdao
| | - Mei Wang
- Key Laboratory of Marine Chemistry Theory and Technology
- Ministry of Education
- College of Chemistry and Chemical Engineering
- Ocean University of China
- Qingdao
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Nitsche S, Schmitz S, Stirnat K, Sandleben A, Klein A. Controlling Nuclearity and Stereochemistry in Vanadyl(V) and Mixed Valent VIV/VVComplexes of Oxido-Pincer Pyridine-2,6-dimethanol Ligands. Z Anorg Allg Chem 2018. [DOI: 10.1002/zaac.201800352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sara Nitsche
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Simon Schmitz
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Kathrin Stirnat
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Aaron Sandleben
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Axel Klein
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
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6
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Madanhire T, Abrahams A, Hosten E, Betz R. Synthesis and characterization of Pr(III), Nd(III) and Er(III) complexes with 2,6-pyridinedimethanol. J COORD CHEM 2017. [DOI: 10.1080/00958972.2017.1376050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Tatenda Madanhire
- Department of Chemistry, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa
| | - Abubak’r Abrahams
- Department of Chemistry, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa
| | - Eric Hosten
- Department of Chemistry, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa
| | - Richard Betz
- Department of Chemistry, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa
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7
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Antibacterial Activity and Cytotoxicity of Silver(I) Complexes of Pyridine and (Benz)Imidazole Derivatives. X-ray Crystal Structure of [Ag(2,6-di(CH2OH)py)2]NO3. Molecules 2016; 21:87. [PMID: 26828469 PMCID: PMC6274122 DOI: 10.3390/molecules21020087] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 01/02/2016] [Accepted: 01/06/2016] [Indexed: 11/16/2022] Open
Abstract
Selected aspects of the biological activity of a series of six nitrate silver(I) complexes with pyridine and (benz)imidazole derivatives were investigated. The present study evaluated the antibacterial activities of the complexes against three Gram-negative strains: Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 25922 and Proteus hauseri ATCC 13315. The results were compared with those of silver nitrate, a silver sulfadiazine drug and appropriate ligands. The most significant antibacterial properties were exerted by silver(I) complexes containing benzimidazole derivatives. The cytotoxic activity of the complexes was examined against B16 (murine melanoma) and 10T1/2 (murine fibroblasts) cells. All of the tested silver(I) compounds were not toxic to fibroblast cells in concentration inhibited cancer cell (B16) viability by 50%, which ranged between 2.44–28.65 µM. The molecular and crystal structure of silver(I) complex of 2,6-di(hydroxymethyl)pyridine was determined by single-crystal X-ray diffraction analysis. The most important features of the crystal packing and intermolecular non-covalent interactions in the Ag(I) complex were quantified via Hirshfeld surface analysis.
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Dermitzaki D, Raptopoulou CP, Psycharis V, Escuer A, Perlepes SP, Stamatatos TC. Nonemployed Simple Carboxylate Ions in Well-Investigated Areas of Heterometallic Carboxylate Cluster Chemistry: A New Family of {CuII4LnIII8} Complexes Bearing tert-Butylacetate Bridging Ligands. Inorg Chem 2015. [DOI: 10.1021/acs.inorgchem.5b01179] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Catherine P. Raptopoulou
- Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 15310 Aghia Paraskevi, Attikis, Greece
| | - Vassilis Psycharis
- Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 15310 Aghia Paraskevi, Attikis, Greece
| | - Albert Escuer
- Departament
de Quimica Inorganica, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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Chans GM, Gómez E, Gómez-Vidales V, Toscano RA, Álvarez-Toledano C. Synthesis, molecular structure, and spectral analysis of copper(II) complexes derived from pyridinediols. J COORD CHEM 2014. [DOI: 10.1080/00958972.2014.982111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Guillermo M. Chans
- Instituto de Química, Universidad Nacional Autónoma de México, México D.F., Mexico
| | - Elizabeth Gómez
- Instituto de Química, Universidad Nacional Autónoma de México, México D.F., Mexico
| | | | - R. Alfredo Toscano
- Instituto de Química, Universidad Nacional Autónoma de México, México D.F., Mexico
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Alexandropoulos DI, Cunha-Silva L, Pham L, Bekiari V, Christou G, Stamatatos TC. Tetranuclear Lanthanide(III) Complexes with a Zigzag Topology from the Use of Pyridine-2,6-dimethanol: Synthetic, Structural, Spectroscopic, Magnetic and Photoluminescence Studies. Inorg Chem 2014; 53:3220-9. [DOI: 10.1021/ic5001045] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
| | - Luís Cunha-Silva
- REQUIMTE & Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Linh Pham
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Vlasoula Bekiari
- Department of Aquaculture and Fisheries Management, Technological Educational Institute of Western Greece, 30 200 Messolonghi, Greece
| | - George Christou
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
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Hexanuclear zinc(II) carboxylate complexes from the use of pyridine-2,6-dimethanol: Synthetic, structural and photoluminescence studies. Polyhedron 2013. [DOI: 10.1016/j.poly.2012.08.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Methylene spacer regulated variation in structures and magnetic properties in copper(II) compounds with O, N, O donor Schiff bases. Polyhedron 2013. [DOI: 10.1016/j.poly.2012.10.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Peresypkina EV, Lider ЕV, Smolentsev AI, Sanchiz J, Gil-Hernández B, Potapov АS, Khlebnikov АI, Kryuchkova NA, Lavrenova LG. Bis(benzotriazol-1-yl)methane as a linker in the assembly of new copper(II) coordination polymers: Synthesis, structure and investigations. Polyhedron 2012. [DOI: 10.1016/j.poly.2012.08.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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El-Boraey HA. Coordination behavior of tetraaza [N₄] ligand towards Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes: synthesis, spectroscopic characterization and anticancer activity. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 97:255-262. [PMID: 22765944 DOI: 10.1016/j.saa.2012.05.077] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/19/2012] [Accepted: 05/29/2012] [Indexed: 06/01/2023]
Abstract
Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N(4)] ligand (L) i.e. 2-amino-N-{2-[(2-aminobenzoyl)amino]ethyl}benzamide have been synthesized and structurally characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and molar conductivity measurements. On the basis of IR, mass, electronic and EPR spectral studies an octahedral geometry has been proposed for Co(II), Ni(II) complexes and Cu(II) chloride complex, square-pyramidal for Cu(I) bromide complex. For Cu(II) nitrate complex (6), Pd(II) complex (8) square planar geometry was proposed. The EPR data of Cu(II) complexes in powdered form indicate d(x2-y2) ground state of Cu(II) ion. The antitumor activity of the synthesized ligand and some selected metal complexes has been studied. The palladium(II) complex (8) was found to display cytotoxicity (IC(50)=25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line.
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Affiliation(s)
- Hanaa A El-Boraey
- Department of Chemistry, Faculty of Science, El-Menoufia University, Shebin El-Kom, Egypt.
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15
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Chen SL, Liu Z, Xia JH, Li YH. Synthesis, crystal structure, and spectroscopic properties of a new Zn(II) coordination polymer with 4-(2-picolinylhydrazide) methylene benzoic acid containing the (H2O)8(CH3OH)2 cluster. J COORD CHEM 2012. [DOI: 10.1080/00958972.2012.690866] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Shi-Liang Chen
- a College of Chemical and Biological Engineering , Guilin University of Technology , Guilin 541004 , P.R. China
| | - Zheng Liu
- a College of Chemical and Biological Engineering , Guilin University of Technology , Guilin 541004 , P.R. China
| | - Jin-Hong Xia
- b College of Electronic Engineering , Guilin University of Electronic Technology , Guilin 541004 , P.R. China
| | - Yan-Hong Li
- c Guangxi Key Laboratory of Environmental Engineering , Protection and Assessment , Guilin 541004 , P.R. China
- d College of Environmental Science and Engineering , Guilin University of Technology , Guilin 541004 , P.R. China
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Chakraborty A, Gurunatha KL, Muthulakshmi A, Dutta S, Pati SK, Maji TK. Assembly of trinuclear and tetranuclear building units of Cu2+ towards two 1D magnetic systems: synthesis and magneto-structural correlations. Dalton Trans 2012; 41:5879-88. [DOI: 10.1039/c2dt12511k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Oxido-pincer complexes of copper(II) – An EXAFS and EPR study of mono- and binuclear [(pydotH2)CuCl2]n (n=1 or 2). Polyhedron 2012. [DOI: 10.1016/j.poly.2011.10.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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El-Boraey HA, Emam SM, Tolan DA, El-Nahas AM. Structural studies and anticancer activity of a novel (N6O4) macrocyclic ligand and its Cu(II) complexes. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 78:360-370. [PMID: 21081283 DOI: 10.1016/j.saa.2010.10.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 09/29/2010] [Accepted: 10/18/2010] [Indexed: 05/30/2023]
Abstract
A novel (N6O4) macrocyclic ligand (L) and its Cu(II) complexes have been prepared and characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and conductivity measurements. Quantum chemical calculations have also been carried out at B3LYP/6-31+G(d,p) to study the structure of the ligand and one of its complexes. The results show a novel macrocyclic ligand with potential amide oxygen atom, amide and amine nitrogen atoms available for coordination. Distorted square pyramidal ([Cu(L)Cl]Cl·2.5H2O (1), [Cu(L)NO3]NO(3)·3.5H2O (2), and [Cu(L)Br]Br·3H2O (4) and octahedral ([Cu(L)(OAc)2]·5H2O (3)) geometries were proposed. The EPR data of 1, 2, and 4 indicate d1x2(-y)2 ground state of Cu(II) ion with a considerable exchange interaction. The measured cytotoxicity for L and its complexes (1, 2) against three tumor cell lines showed that coordination improves the antitumor activity of the ligand; IC50 for breast cancer cells are ≈8.5, 3, and 4 μg/mL for L and complexes (1) and (2), respectively.
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Affiliation(s)
- Hanaa A El-Boraey
- Department of Chemistry, Faculty of Science, El-Menoufia University, Shebin El-Kom, Egypt
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Kharat AN, Bakhoda A, Hajiashrafi T. Catalytic oxidation of organosulfides to sulfoxides using two novel Cu(II) and Ni(II) complexes with aqueous H2O2: Effect of TMAO promoter on oxidation of organosulfides. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.molcata.2010.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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21
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Papatriantafyllopoulou C, Stamatatos TC, Wernsdorfer W, Teat SJ, Tasiopoulos AJ, Escuer A, Perlepes SP. Combining azide, carboxylate, and 2-pyridyloximate ligands in transition-metal chemistry: ferromagnetic Ni(II)5 clusters with a bowtie skeleton. Inorg Chem 2010; 49:10486-96. [PMID: 20964448 DOI: 10.1021/ic1014829] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The combined use of the anion of phenyl(2-pyridyl)ketone oxime (ppko(-)) and azides (N(3)(-)) in nickel(II) carboxylate chemistry has afforded two new Ni(II)(5) clusters, [Ni(5)(O(2)CR')(2)(N(3))(4)(ppko)(4)(MeOH)(4)] [R' = H (1), Me (2)]. The structurally unprecedented {Ni(5)(μ-N(3))(2)(μ(3)-N(3))(2)}(6+) cores of the two clusters are almost identical and contain the five Ni(II) atoms in a bowtie topology. Two N(3)(-) ions are end-on doubly bridging and the other two ions end-on triply bridging. The end-on μ(3)-N(3)(-) groups link the central Ni(II) atoms with the two peripheral metal ions on either side of the molecule, while the Ni···Ni bases of the triangles are each bridged by one end-on μ-N(3)(-) group. Variable-temperature, solid-state direct- (dc) and alternating-current (ac) magnetic susceptibility, and magnetization studies at 2.0 K were carried out on both complexes. The data indicate an overall ferromagnetic behavior and an S = 5 ground state for both compounds. The ac susceptibility studies on 1 reveal nonzero, frequency-dependent out-of-phase (χ(M)") signals at temperatures below ~3.5 K; complex 2 reveals no χ(M)" signals. However, single-crystal magnetization versus dc field scans at variable temperatures and variable sweep rates down to 0.04 K on 1 reveal no noticeable hysteresis loops, except very minor ones at 0.04 K assignable to weak intermolecular interactions propagated by nonclassical hydrogen bonds.
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